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Montana Animal Field Guide

Montana Field Guides

Utah Chub - Gila atraria

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Exotic Species (not native to Montana)

Global Rank: G5
State Rank: SNA

Agency Status


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General Description
Utah chub were introduced into Montana in the 1930's, probably by bait fishermen. They were released into Hebgen Lake, a headwater reservoir on the Missouri River system, and have since extended their range about 200 miles downstream. In time, they could even move into North Dakota. Utah chubs are omnivorous and can grow to a size of up to 2 pounds. They are considered to be a very undesirable fish. In some reservoirs, they have become very abundant and may compete for food with trout. These chubs can become too large to be preyed upon by trout and are annoying because they readily take fishermen's bait.

Diagnostic Characteristics
Back olive brown to nearly black, occasionally bluish; sides usually brassy but sometimes silvery. Underside whitish or silver. No barbels.

Species Range
Montana Range

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Summary of Observations Submitted for Montana
Number of Observations: 1322

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Found to move at least short distances up streams and tributaries in Hebgen Lake Study.

Very generalized habitat requirements. Found in both stream and lakes with abundant aquatic vegetation. Prefers slow-moving or still water as in sloughs backwaters, and reservoirs. Spawns in littoral waters.

Food Habits
Young feed largely on zooplankton. Adults become onmivorous utilizing aquatic plants, insects, and crustaceans.

Rooted aquatic vegetation important for spawning and rearing areas. Adult chubs found in 1978 Montana study were not associated with aquatic vegetation.

Reproductive Characteristics
Sexually mature: males in 3 yrs, and females in 4 years. Spawns in mid-May - mid-Aug. in Hebgen Lake when water temp. exceeds 54 degrees F. with late June - early July peak.

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Citation for data on this website:
Utah Chub — Gila atraria.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on October 9, 2015, from
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